A black shape emerges from the misty shadows of the night and slinks up to the door. A glint of light flashes from a knife. There’s a scratching sound as the man begins to whittle a symbol into the wood. You probably won’t be able to read what he’s carving, because it’s in a centuries-old secret language: the tramp signs of Europe.

Frequently used from the 17th to 19th centuries, these symbols provided secret information to other criminals and vagabonds. Tramp signs told which houses provided refuge and which were dangerous. Even if a criminal was illiterate, he could still read these symbols.

By the 20th century, law enforcement had deciphered many of the symbols. Here are few listed in a criminal investigator’s handbook:

Historical tramp signs from Europe.

Some of these symbols became the basis for the hobo symbols that flourished in North American starting in the late 19th century and through the Depression. Compare the tramp signs above to some of these hobo symbols from North America:

Ryan Somma, Key to a few hobo signs, National Cryptologic Museum, Creative Commons.

In Europe, however, tramp signs were also used by mischief-makers who were much more dangerous than hobos. Some tramp signs would tell a criminal which house to burglarize, which to burn, or even which occupants to murder. Here are two ominous examples from 19th century Europe:

Instructions to commit murder by arson found on a chapel in the forest in Germany. The first line means “In the night of the last quarter moon, the fourth house in the direction of the arrow will be attacked.” The symbols on the bottom line are the signatures of the participants. From Hans Gross, Handbuch, 1899.

These symbols indicate plans to burglarize the church on Christmas night. The stones and the child wrapped in swaddling clothes indicate the date. Hans Gross, Handbuch, 1899.

In the modern age of cell phones, the need for such communication has largely died out, although police do occasionally still find tramp signs. In 2009, police in Vienna found several on houses, mailboxes, fences, and doors. You can view photographs here. One of the symbols used looked like an upside down table. That means “old people live here.”

A modern variation of tramp signs is warchalking, symbols on streets or lampposts indicating the availability of an open wireless access point.

Sherlock Holmes had his magnifying glass. A modern detective will bring things like evidence tags, fingerprint kits, and latent bloodstain reagents.

What did a 19th-century detective pack into his forensic kit to bring to a crime scene?

Hanns Gross (sometimes spelled Hans Gross), the Austrian father of criminology. Public domain.

Let’s ask Hanns Gross (1847-1915), an Austrian who established forensic science as an academic discipline. Gross studied law and worked as a detective (Untersuchungsrichter) before founding the first university institute of criminology. His Handbuch für Untersuchungsrichter (Handbook for Criminal Investigation), a field book for criminal investigators that was published in 1893, caused a global tsunami in police work, washing away outdated techniques. Gross integrated science and psychology into criminal investigations. He also developed the field of crime scene photography. In translated form, the Handbook became a standard work worldwide.

In the Handbook, Gross lists the items a detective should keep packed in his forensic kit in order to be ready to process a crime scene at a moment’s notice. The list is long, but here are some of the important contents:

paper for taking notes

pen and pencil, ink

ruler or measuring tape

pair of compasses for measuring minute distances

pedometer for measuring distance in paces

transparent paper for tracing outlines, drawings, and blood splatter

plaster to make casts

test tubes for samples of stomach contents of dead bodies to test for arsenic

candles for illumination during nighttime investigation

crucifix for the purposes of putting a dying witness under oath for a statement

directional compass to provide orientation for the detective’s sketch of the crime

bars of soap, not only for washing, but for taking impressions of small items like keys

brush for cleaning debris out of a footprint before taking a cast

magnifying glass

tape, to which small traces of evidence adhere

candy for calming children and inducing them to make statements

first-aid kit, for victims or the detective himself

Yum, old fashioned candy! Hanns Gross recommended investigators bring candy to the crime scene. It can induce children to give statements.

Which of these items seem old-fashioned? And which were ahead of their time? Do you think anything’s missing?

Hanns Gross’ depiction of a detective bag to contain the forensic kit. Public domain.

Because Hanns Gross developed criminal investigation photography, I was surprised not to see a camera on his list. He might have included that in later editions of his book.